Tickler assembly for riser pipe of fused salt electrolysis cell for the production of sodium



Feb. 24, 1970 E. w. BERRY 3,497,447 RISER PIPE OF FUSED S TICKLER ASSEM Y FOR ELECTROLYSIS' 0 FOR THE PRODUCTION s01) Filed July 21, 1

' F I G. 4

mvsmox ELIIER I. BERRY United States Patent 3,497,447 TICKLER ASSEMBLY FOR RISER PIPE 0F FUSED SALT ELECTROLYSIS CELL FOR THE PRODUC- TION 0F SODIUM Elmer W. Berry, Memphis, Tenn., assignor to E. I. du Pont de Nemours and Company, Wilmington, Del., a corporation of Delaware Filed July 21, 1967, Ser. No. 655,185 Int. Cl. Blllk 3/00; C22d 3/06 US. Cl. 204--279 6 Claims ABSTRACT OF THE DISCLOSURE A tickler assembly for the riser pipe of a fused salt electrolysis cell for the production of sodium comprising (A) a tickler for insertion into the top of the riser pipe and operable therein to free solid deposits, e.g., calcium deposits, from the inner walls of the riser pipe, in combination with (B) driving means, preferably a doubleacting gas cylinder, for imparting reciprocal vertical movement to the tickler and (C) a cam in combination with a ratchet for imparting partial rotary movement of the tickler during each vertical movement thereof in the same vertical direction, together with (D) means, preferably a differential pressure pilot-operated reversing valve, for intermittently reversing the direction of the drive of driving means (B). The tickler assembly also includes means for bringing the vertical movement of the tickler to a sudden jarring stop to cause dislodgement of solids from the tickler. Preferably, the tickler assembly for the riser pipe is operated in conjunction with an agitator assembly for a sodium receiver into which sodium passes from the top of the riser pipe into the receiver by way of a weir connecting the two. The agitator assembly for the receiver comprises a rotary agitator including scraper blades for cleaning the side walls of the receiver and the weir between the riser pipe and receiver, and a reversible drive means, preferably a double-acting gas cylinder, in association With a ratchet, for intermittently rotating the agitator.

BACKGROUND OF THE INVENTION Sodium is produced commercially by the electrolysis of a fused electrolyte comprising sodium chloride in an electrolysis cell of the Downs type, described in Downs US. Patent 1,501,756. Such cells generally employ bottom-mounted vertical cylindrical anodes surrounded by cylindrical cathodes so that each cathode and anode combination defines an annular electrolysis Zonein which is positioned a foraminous diaphragm serving to separate the electrolysis products from each other. The chlorine product rises from the anode through the electrolyte into a hood from which it is withdrawn from the cell. The sodium product rises from the cathode through the electrolyte into a collector, generally an inverted annular trough, from which the sodium rises further into a vertical riser pipe which conveys the sodium out of the upper part of the cell and into a receiver.

Because of the high melting point of sodium chloride, it is customary to employ as the electrolyte a mixture of sodium chloride and one or more other metal chlorides such as calcium chloride, the function of the latter being to lower the melting point of the electrolyte thus permitting operation of the cell at a lower temperature. The use of such a mixture of chlorides as the electrolyte results in a sodium cathode product which contains another metal, e.g., calcium, as impurity. As the sodium rises from the cell through the riser pipe, the upper portion of which is generally provided with cooling fins, most of the second metal, such as calcium, will precipitate as a solid from the sodium and, because of its greater density, will sink in the riser pipe and return to the body of electrolyte. Calcium returned to the electrolyte in this manner reacts with the sodium chloride present to produce metallic sodium and calcium chloride. Thus, the function of the riser pipe is that of purifying the sodium product so that the sodium which passes from the top of the riser pipe into the receiver will contain only small amounts of metal impurities such as calcium. The impurities which are precipitated in the riser pipe tend to deposit as a solid on the inner walls of the pipe. If such solid deposits are not removed, they eventually would completely plug the riser pipe. It is, therefore, essential that such deposits be removed at least periodically from the riser pipe Walls. This is customarily done by the use of devices, commonly referred to as ticklers, which are generally operated on a periodic basis. Various types of mechanically driven ticklers have been proposed, for example, in US. Patents 2,770,364; 2,770,592; 2,861,938 and 3,037,927.

The above patents describe tickler assemblies which combine various types of ticklers with certain mechanisms for mechanically driving the ticklers. The tickler usually consists of a shaft which is generally coextensive in length with the length of the riser pipe except for a portion of the shaft which extends through the top of the riser pipe for connection with the driving mechanism. The shaft in the riser pipe is usually provided with cleaner blades or scrapers designed to remove solids from the inner walls of the riser pipe as the shaft is driven vertically and/or rotated by the driving mechanism. The type of cleaner blades or scraper elements of the ticklers which have been proposed include a plurality of cutting hoops designed to scrape the riser pipe wall when the tickler is moved vertically, blades in the form of paddles positioned in spaced relationship along the vertical length of the tickler shaft, scraper blades of arcuate shape with a forward cutitng edge, and vertically disposed scraper blades having cutting edges. All such scraping or cleaning elements are intended generally to exert a scraping action over the entire inner surface of the riser pipe during the operation of the tickler.

While the tickler assemblies described in the above patents are useful, their scraping action is not as effective as desired, particularly for breaking up and removing solid encrustations from the riser pipe walls. Furthermore, they are not designed to handle simultaneously the removal of solids from the walls of the sodium receiver and from the weir or opening between the receiver and the riser pipe, and they require relatively frequent repair or changing and considerable manual attention during operation.

The present invention relates to an improved mechanical tickler assembly, preferably in association with a sodium receiver agitator assembly, in which tickler assembly is employed an improved driving mechanism assuring a long effective life with essentially no manual attention being required.

As indicated above, the sodium product rising in the riser pipe of a Downs type cell flows from the riser pipe into a product receiver, generally by way of an opening or weir connecting the riser pipe with the product receiver. The sodium delivered into the receiver generally has a relatively low calcium content. Nevertheless, precipitation of calcium on the walls of the receiver does occur and calcium deposits tend to block passage of the sodium through the weir. The combination of the tickler assembly of the present invention with the receiver agitator assembly is designed not only to remove solid deposits such as calcium from the inner walls of the riser pipe, but also to remove such deposits from the walls of the receiver and from the weir connecting the riser pipe and the receiver.

3 SUMMARY OF THE INVENTION The riser pipe tickler assembly of the invention comprises (A) a tickler for insertion into the top of a sodium riser pipe and operable therein to free solid deposits from the inner walls of the riser pipe, in combination with (B) driving means for imparting reciprocal vertical movement to the tickler, (C) a cam in combination with a ratchet for imparting partial rotary movement of the tickler during each vertical movement thereof in the same vertical direction, and (D) means for intermittently reversing the direction of the drive of driving means (B). The tickler assembly also includes means for bringing the vertical movement of the tickler to a sudden jarring stop.

In a preferred embodiment of the invention, the above tickler assembly is operatively combined with an agitator assembly for a sodium receiver connected to the riser pipe by way of an opening or weir through which sodium fiows from the riser pipe into the receiver, which agitator assembly comprises an agitator which is rotatable within the receiver and includes blades for cleaning the receiver side walls and said weir, in combination with means for intermittently rotating the agitator in one direction, which means comprises a driving means in combination with a ratchet, and means for intermittently reversing the direction of the drive of the driving means.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a preferred embodiment of the riser pipe tickler assembly of the invention showing also a sodium receiver provided with an agitator assembly in accordance with the invention.

FIG. 2 is a front view, shown partly in elevation and partly in section, of the riser pipe tickler assembly and receiver agitator assembly of FIG. 1.

FIG. 3 shows diagrammatically the pneumatic system employed for operating the assemblies of FIG. 1.

FIG. 4 is a view shown mainly in cross-section but partly in elevation of a differential pressure pilot-operated. reversing valve.

FIG. 5 is a motion diagram depicting the vertical and rotary movements of the tickler of FIG. 2 under normal operating conditions.

FIG. 6 is a motion diagram depicting the rotary movements of the tickler of FIG. .2 under normal operating conditions.

FIG. 7 is a motion diagram depicting the vertical and rotary movements of the tickler of FIG. 2 when the tickler encounters obstinate solid obstructions during its operation.

Before describing in detail the structures of the drawings, it should be pointed out that the riser pipe of a sodium cell of the Downs type rises from Within the cell and extends vertically for a considerable distance above the cell where it discharges into a sodium receiver. Generally, the upper part of the riser pipe, which is external of the cell, is provided with cooling fins in order to facilitate cooling of the rising column of sodium so as to effect precipitation of metal impurities therefrom. On the other hand, the bottom portion of the riser pipe which is internal of the cell is usually somewhat smaller in diameter than the external part of the riser pipe, which bottom part opens into the sodium collector positioned above the cell cathode. The general arrangement of the riser pipe with respect to the sodium cell is Well understood and is shown in the drawings of most of the patents referred to above. Accordingly, the accompanying drawings do not show the association of the riser pipe with the sodium cell, it being understood that the association is the usual one indicated in the patents referred to above.

FIGS. 1 and 2 show a riser pipe 100 Whose upper part is provided with cooling fins and whose lower part is of somewh t smaller diameter than the upper part, which upper and lower parts are connected by a restricted portion 101. Extending through the riser pipe is a tickler shaft 102 which is generally coextensive in length with the length of the riser pipe except that its upper end extends through cover plate 103 and terminates at tickler clamp 104. Shaft 102 is provided with tickler blades 105 arranged in pairs mounted on the shaft at regular intervals throughout the shaft length. The tickler blades of each pair are mounted on shaft 102 at substantially right angles thereto. They are generally rectangular in shape, with the length of each blade being such that the spacing between its outer end and the wall of the riser pipe is but a fraction of an inch, e.g., about inch. Each blade of a pair is mounted on the shaft 180 from the other blade of that pair. Preferably, all pairs of blades are mounted in the same vertical plane. In general, the length of each blade is 4 to 7 times its width and their construction of steel bars or plate about A1 to inch thick insures sufiicient ruggedness for the operation intended.

Reciprocal vertical movement of the tickler is imparted by the action of a double-acting gas cylinder 106, whose drive shaft is operatively coupled to tickler shaft 102 by clamp 104, while partial rotation of the tickler in a single direction during each up or down movement thereof is imparted by fixed cam 107 in conjunction with ratchet 108 attached to the drive shaft of gas cylinder 106. Intermittent reversal of the direction of the drive of gas cylinder 106 is effected by differential pressure pilotoperated reversing valve 109, sometimes referred to hereinafter simply as the pilot valve.

Shown associated with riser pipe is sodium receiver 110, the upper part of which is connected to the riser pipe through weir 111. Receiver 110 is provided with an agitator 112 whose shaft 121 extends through cover 122 and has attached at its top end ratchet 120 which is operatively connected to the drive shaft of double-acting gas cylinder 114. Agitator 112 is provided with scraper blade 113 which extends or sweeps into weir 111 during its rotation with just enough clearance being provided between blade 113 and upper-most tickler blade so as to permit both blades to rotate simultaneously. The purpose of receiver agitator 112 is to keep suspended the calcium deposits that are formed in the sodium in receiver so that they will be removed along with the sodium as the latter flows out of the bottom (not shown) of the receiver. Rotation of agitator 112, including blade 113, and the rotation of the top riser pipe tickler blade 105 cooperate to clear solid deposits from weir 111, thereby permitting free flow of sodium from the riser pipe into the receiver. Receiver agitator 112 also functions to scrape off solid deposits that may tend to accumulate on the inner walls of receiver 110.

Agitator 112 is intermittently rotated in a single direction by means of double-acting gas cylinder 114 operating in conjunction with ratchet 120 and pilot valve 109. Activation of gas cylinder 106 through pilot valve 109 drives tickler shaft 102 reciprocally up and down, while a partial rotation of shaft 102 during each of the up or the down movements thereof is effected by the action of fixed cam 107 and ratchet 108. Ratchet 108 has an arm terminating in cam follower 115 which operates in cam slot 116 of cam 107 Cam 107 is curved as indicated in FIG. 1 and can be conveniently fabricated out of a section of pipe of suitable diameter. Thus, such a section of pipe of suitable diameter can be split so as to leave a trough-shaped portion as indicated in FIG. 1 in which portion cam slot 116 is cut. The slope of cam slot 116 and the length of the stroke of air cylinder 10'6 determine the amount of rotation of the tickler during each up or down movement thereof.

As shown in FIG. 3, double-acting gas cylinders 106 and 114 are connected by gas lines 117 so as to be controlled by a differential pressure pilot-operated reversing valve 109 which is connected to a gas supply by gas supply line 118 having valve 119 therein. Thus, air under suitable pressure admitted to the system through valve 119 and supply line 118 passes by way of pilot valve 109 and gas lines 117 to double-acting gas cylinders 106 and 114 which activate tickler shaft 102 and receiver agitator 112, respectively. Besides causing tickler shaft 102 to reciprocate vertically, gas cylinder 106 causes a partial rotation of shaft 102 through its action in conjunction with hatchet 108 and cam 107, during each of either the up or down movement of the shaft. The rotary movement is preferably a rotation of about 80, but the extent of the rotation can be varied as desired. The rotation will always be in the same direction provided the setting of the ratchet remains unchanged. Activation of double-acting gas cylinder 114 together with ratchet 120 effects intermittent rotation of receiver agitator 112,

Ratchets 108 and 120 are preferably of the reversible type whereby the rotations of tickler shaft 102 and receiver agitator 112 may be reversed if desired. However, unless the settings of the ratchets are changed the tickler and the receiver agitator will always rotate unidirectionally. Preferably, the setting of ratchet 108 will be such that the tickler will rotate, e.g., about 80, during each down stroke but will be lifted straight up without any turning during each up stroke. However, by reversing the setting of ratchet 108, the tickler can be made to rotate in the opposite direction during the up stroke with no rotation occuring during the downstroke. Similarly, depending upon the setting of ratchet 120, the intermittent rotation of receiver agitator 112 can be made to occur either clockwise or counter clockwise.

It will be seen from FIG. 3 that differential pressure pilot-operated reversing valve 109 serves to control the operation of both double-acting gas cylinders 106 and 114, which pilot valve is set into operation simply by opening valve 119 to admit air under pressure into the pneumatic control system of FIG. 3. When operation of the system is no longer needed, valve 119 is simply closed whereby the operation stops. The opening and closing of valve 119 can be readily made to occurautomatically at any desired periodic intervals by the programming thereof with a timer, When valve 119 is open so that the pneumatic control system is in operation, the reversing of the drives of gas cylinders 106 and 114 will automatically be controlled by the piloting action of pilot valve 109. Thus, when valve 119 is open, gas cylinder 106 will automatically effect the reciprocal vertical movement of the tickler in the riser pipe while, simultaneously, gas cylinder 114 will automatically effect the intermittent rotation of receiver agitator 112. How pi ot valve 109 functions to effect such automatic control will be apparent from FIG. 4 and the following description thereof.

FIG. 4 shows the essential structural features of a differential pressure pilot-operated reversing valve of the type that is usable as pilot valve 109 in the pneumatic control system of FIG. 3. Such pilot valves are well known and available commercially. In FIG. 4, the body of the valve, shown in cross-section, will include a bore in which a piston with parts X, Y and Z moves in such manner as to reverse the flow of a gas under pressure (supplied to the valve) to one or the other of two delivery ports. As shown in the drawing, gas of suitable pressure is supplied by way of gas .line 118 to valve inlet port A. If piston part Z is at the right end of the bore of the valve, piston parts Y and X will be in the positions shown so as to permit flow of gas as indicated by the solid arrows from inlet port A through the valve to delivery port B. At the same time, the gas will fill up pilot channel G which is plugged by plunger W loaded with spring V. The delivery of gas under pressure via delivery port B to gas cylinder 106 and gas cylinder 114 will continue until gas cylinder 106 reaches the end of its stroke, or until the tickler becomes stuck, whereupon the air pressure will build up in channel G until it reaches a certain set value. At that point, spring V will be overcome allowing plunger W to rise whereby the flow of the gas under pressure into chamber H will move piston parts Z, Y and X to the left at the positions indicated by Z, Y and X, respectively. When that happens, the flow passage in the left side of the valve will be closed while the passage on the right side will be opened to permit the flow of gas as indicated by the broken arrows from inlet port A to delivery port C from which the gas will then flow to the opposite ends of gas cylinders 106 and 114 so as to reverse the direction of their drives. When gas cylinder 106 again reaches the end of its stroke, or if the tickler becomes stuck again, the air pressure in the right flow passage of the pilot valve will build up through pilot channel F so as to overcome spring T and raise plug U where'by gas under pressure admitted to chamber I will force piston parts X, Y and Z to the right side again so that the flow of the gas through the left side of the valve will be repeated. Thus, the delivery of a gas, such as air, under pressure will alternate between delivery ports B and C as long as the gas is supplied at suitable pressure through supply line 118 with the result that the drives of gas cylinders 106 and 114 will be repeatedly reversed according to a sequence depending upon the pressure of the gas supplied through line 118 and the length of the stroke of gas cylinder 106. Gases from chambers H and I are exhausted at the appropriate times via exhaust ports D and B, respectively. Exhaust ports D and E also serve to exhaust gases from the non-driving sides of air cylinders 106 and 114.

In the operation of the tickler assembly and receiver agitator assembly illustrated in FIGS. 1 and 2 and controlled by the pneumatic system of FIG. 3, the normal movement, both vertical and rotary, of the riser pipe tickler during the period of its operation is that depicted by the motion diagram of FIG. 5. As there indicated with the tickler starting at the top of a stroke in position 1 its movement downward would be along line 12 representing both a downward and a partial rotary movement due to the action of ratchet 108 in conjunction with cam 107. As the tickler reaches the bottom of the stroke at position 2, it would come to a sudden jarring stop due to the contact of clamp 104 with riser pipe cover plate 103. At that point, pilot valve 109 would cause the reversal of gas cylinder 106 which would then effect the vertical movement of the tickler from position 2 to 3. Due to the setting of ratchet 108 there would be no rotary movement of the tickler during the movement from 2 to 3. Upon reaching position 3, however, pilot valve 109 would again cause reversal of the vertical movement of the tickler whereby it would then move from position 3 to 4 and would also be rotated partially in doing so. It would then follow in sequence corresponding movements from positions 4 to 5, from 5 to 6, from 6 to 7, etc., with each movement from the bottom to the top being a straight vertical movement without rotation and each movement from the top to the bottom being both a vertical movement and a partial rotary movement, assuming that no hard encrustations of solid deposits are encountered in the riser pipe.

The circular position of the paddle blades of the tickler at the beginning of each up stroke thereof would be as indicated in FIG. 6. Thus, at the beginning of the first down stroke the blades would be in position 1, whereas at the beginnings of succeeding up strokes they would be in the positions 2, 3 then 4, 5, then 6, 7, etc., going around the circle. In other words. at the beginning of each up stroke the tickler blades would be in a new circular position with the result that as the operation progresses all surfaces of the riser pipe would eventually be subjected to the chopping or cutting action of the upper edges of the tickler blades. Similarly, the position of the tickler blades at the beginning of each down stroke of the tickler would be in a different circular position with the result that all surfaces of the riser pipe would eventually be subjected to the slicing action of the tickler blades during the downward movements. Thus, solid deposits on the inner walls of the riser pipe are subjected alternately and succesively to a vertical chopping action and to an oblique slicing action, both of which types of action are highly effective in removing or loosening solid deposits from the wall surfaces.

There occasionally occurs times when the solid deposit on the riser pipe wall may be rather difficult to dislodge and may not be dislodged upon its first contact with the tickler blades during the operation of the tickler. FIG. 7 is a motion diagram depicting the movements of the tickler as they would occur when such a solid deposit is encountered. In FIG. 7, obstinate or difficulty dislodged solid deposits are indicated by small triangles. In the diagram, positions indicated by even numbers represent the bottoms of the vertical strokes, whereas the odd numbers indicate the tops of the vertical strokes. As an obstinate obstruction is met at position 3 after the tickler has moved from a starting position of from 1 to 2, pilot valve 109 would cause the reversal of gas cylinder 106 so that the movement would then be from position 3 to position 4 where another obstinate obstruction is met, whereupon reversal would again occur causing a movement from position 4 to position 5. As seen from FIG. 7, a reversal of the drive of gas cylinder 106 will occur at the tops and the bottoms of the normal strokes or whenever an obstinate solid obstruction is encountered in the movement of the tickler. Since each full or part down stroke includes a partial rotation of the tickler as indicated in going from an odd-numbered position to an evennumbered position in the diagram, the tickler will, in its continuous operation, subject any given obstinate deposit encountered to the repeated chopping and slicing actions of the tickler blade, whereby the obstinate article will eventually become loosened from the wall surface. No manual resetting of any of the controls is needed and the net effect of controlling the reversing action of gas cylinder 106 by pilot valve 109 is that the system will automatically function to remove almost any solid obstruction from the wall surfaces of the riser pipe no matter how tenaciously it may be held on the wall surface. In practical application, the tickler assembly of FIGS. 1 and 2, in conjunction with the pneumatic control system of FIG. 3, will automatically operate in essentially the same way that a man would operate a similar tickler to take care of situations where the forward motion of the tickler becomes impeded by solid deposits. The operation becomes automatic because of the unique control action exercised by pilot valve 109. The operation of the tickler is much more effective when using the driving mechanism of FIGS. 1 and 2 than it would be if the tickler were manually operated.

Due to the connection of gas cylinder 114 onto the control system of FIG. 3, which also controls the operation of gas cylinder 106, a reversal of the drive of the latter gas cylinder will also cause a reversal of the drive of gas cylinder 114 which activates receiver agitator 112. Since air cylinder 114 activates agitator 112 through ratchet 120, agitator 112 will intermittently be rotated somewhat freely then remain stationary as the drive of the gas cylinder is repeatedly reversed. As indicated previously, the degree of rotation of the tickler during its down stroke will be governed by the slope of cam slot 116 and the length of the stroke of air cylinder 106. The extent of the rotation can be controlled as desired, but generally a partial rotation of 35-135 is adequate with a rotation of 70-100" being perferred. Most preferably, the degree of rotation during each down stroke of the tickler will be such that the angle of rotation during each down stroke, when divided into 360, will give an odd number. This is distinctly preferred because with such an angle of rotation, the starting position of the tickler for each vertical movement will be different.

Th m gnit de of the p and down movement of the tickler will, of course, be limited and generally will not exceed about 6 inches. The preferred vertical movement will generally be about 2 to 4 inches, and the vertical spacing of the tickler blades upon the tickler shaft will be such that when the tickler is in its bottom-most position, the upper tickler blade will be opposite weir 111. The rotation of the upper-most tickler blade will cooperate with the rotation of agitator blade 113 to keep weir 111 free of excessive solid deposits.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred tickler assembly for the riser pipe will be that described above and represented by FIGS. 1, 2 and 3. As indicated in the above description, the preferred means for driving the tickler is a double-acting gas cylinder, 106. Similarly, the preferred means for intermittently rotating receiver agitation 112 will be a double-acting gas cylinder, 114, both of which gas cylinders will be activated by gas supplied under suitable pressure through a differential pressure pilot-operated reversing valve, 109. Regular periodic operations of the tickler assembly and the receiver agitator assembly can be readily made to occur automatically by programming the operations with a timer. When so programmed, the perferred tickler and receiver agitator assemblies represented by FIGS. 1, 2 and 3 are usable with essentially no manual control or attention being required during the full life of a cell diaphragm which may range from a few days to days or longer, but generally will average about 40 days. If the tickler operation are programmed manually, no manual attention other than for the periodic starting and stopping of each operation will generally be necessary over the entire period of the diaphragm life. When a new diaphragm is required, the top part of the cell must be removed for the insertion of a new diaphragm and any repair or replacement of parts of the upper part of the cell that is required is made at that time. Therefore, when the life of a tickler assembly is at least as long as the diaphragm life, the latter rather than the tickler life becomes controlling and that is the case when using the tickler assembly of the present invention.

While FIG. 2 shows a tickler provided with paddle type blades spaced vertically along the tickler shaft, such blades may be replaced by other suitable scraping or cleaning devices. Thus, instead of the paddle type blades shown in FIG. 2, the cleaning or scraping device may consist of similar blades with adjacent pairs thereof connected together in alternate manner by a single vertical strip at their outer ends so that upon rotation of the tickler all surfaces of the inner walls of the riser pipe will be simultaneously scraped or wiped. Also, tickler scraping elements in the form of helical blades, scraping hoops or a plurality of vertically disposed blades uniformly spaced about the tickler shaft can be used, although tickler blades of the paddle type indicated in FIG. 2 are distinctly preferred because of their simplicity and ease of forming and their generally high effectiveness.

Instead of driving the gas cylinders of FIGS. 1 and 2 with air under pressure, other suitable gases such as nitrogen may be employed. Furthermore, instead of double-acting gas cylinders as the driving means, reversible electric motors with suitable switching mechanisms, air or gas motors or hydraulic cylinders may be employed. Also, in place of pressure differential pilotoperated reversing valve .109 of the drawings, other suitable piloting means such as solenoid valves with appropriate switching mechanisms can be used. However, the pneumatic driving and valving mechanisms described above are distinctly preferred for cost reasons and for their generally efficient operation in conjunction with the tickler and receiver agitator described.

I claim:

1. A mechanical tickler assembly for use in a vertical riser pipe of a fused salt electrolysis cell for the production of sodium, said assembly comprising (A) a tickler for insertion into the top of said riser pipe and operable therein to free solid deposits from the inner walls of said riser pipe, in combination with (B) driving means for imparting reciprocal vertical movement to the tickler, (C) a cam in combination with a ratchet for imparting partial rotary movement of the tickler during each vertical movement thereof in the same vertical direction, and (D) means for intermittently reversing the direction of the driving means (B).

Z. A tickler assembly in accordance with claim 1 wherein said driving means (B) is a double-acting gas cylinder and means (D) for intermittently reversing the direction of the drive of driving means (B) is a diiferential pressure pilot-operated reversing valve, and wherein said assembly includes means for bringing the vertical movement to a sudden jarring stop.

3. A tickler assembly in accordance with claim 2 wherein the tickler comprises a drive shaft extending substantially the entire length of the riser pipe and having mounted thereon a plurality of pairs of cleaner blades projecting at substantially right angle from said shaft and spaced at regular intervals along its length with all said blades being in the same vertical plane.

4. A tickler assembly in accordance with claim 1 in association with an agitator assembly for use in a sodium receiver connected to the upper part of the riser pipe by a weir through which sodium product flows from said riser pipe into said receiver, said agitator assembly comprising (Z) an agitator rotatable within said receiver and including blades for cleaning the side walls of said receiver, and (Y) means for intermittently rotating said agitator in one direction.

5. A tickler assembly in association with a receiver agitator assembly in accordance with claim 4 wherein the tickler for the riser piper includes a pair of paddle blades operable to rotate opposite the Weir connecting the riser pipe and the sodium receiver, and wherein the agitator of the receiver agitator assembly includes a blade operable to rotate through said weir, whereby upon rotation of said tickler and said receiver agitator solids accumulated in said weir are removed therefrom.

6. A tickler assembly in association with a receiver assembly in accordance with claim 5, wherein driving means (B) in the tickler assembly is a double-acting gas cylinder and means (D) of the tickler assembly for intermittently reversing the direction of the drive of said driving means (B) of the tickler assembly in a differential pressure pilot-operated reversing valve.

References Cited UNITED STATES PATENTS 2,068,681 l/l937 Hulse et al 204247 2,770,592 11/ 1956 'Fentress 2042A5 2,861,938 11/1958 Glascodine 204243 2,944,950 7/1960 Hayes 20468 2,944,955 7/ 1960 Fentress 204--245 3,037,927 6/1962 Gallinger 204-245 JOHN H. MACK, Primary Examiner D. R. JORDAN, Assistant Examiner US. or. X.R, 204-- 68, 245

mg UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No. 3, 37,? Dated Fe bru anv 2 1970 Inventor(s) Elmer W. Berry It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

In col. 9, line 10, change "driving means" to drive of driving means In col. 10, line 3, change "piper" to pipe line 12, change "in" to of and line 15, change "in" to is SIGNED AN SEALED AUG 1 H970 (SEAL) Amt:

ma-ml:- mm: x. Barium, m.

coma-lion at Ma 

